This is part of my assembly:

[assembly: ComVisible(true)]

[assembly: ClassInterfaceAttribute(ClassInterfaceType.None)]

// The following GUID is for the ID of the typelib if this project is
exposed to COM
[assembly: Guid("cd099def-f9fb-407f-b793-9db68f6b8a0b")]

This is my code:

using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
using System.Globalization;

namespace ExtraStuff
{
    [Guid("4E3BBC1B-625F-47bf-BE80-DAB84F1934BE"),
        InterfaceType(ComInterfaceType.InterfaceIsIDispatch),
        ComVisible(true)]
    public interface IExtraStuff
    {
        [DispId(1)]
        double F2C(double val);
    }
   
    [Guid("F88DAD68-578A-4e23-BCFF-0FBBEC1C4B55"),
        ClassInterface(ClassInterfaceType.None),
        ComSourceInterfaces(typeof(IExtraStuff)),
        ComVisible(true)]
    public class ExtraStuffClass : IExtraStuff
    {
        public ExtraStuffClass()
        {                   
        }
       
        public double F2C(double val)
        {
            return ((5.0/9.0) * (val - 32.0));
        }
    }   
}

and excel vb code:

Option Explicit

Public Function F2C(val As Double) As Double
   Dim ccw As ExtraStuff.IExtraStuff
   Set ccw = New ExtraStuffClass
   F2C = ccw.F2C(val)
End Function

I put my dll to C:\Program Files\Microsoft Office\OFFICE11\ and I registered
that by:

regasm /tlb /codebase ExtraStuff.dll

And when I'm trying use it I get error:

'Run-time error '-2147024894 (80070002)'

In oleview.exe raport everything seems to be OK. Can anyone solve my problem
?